The disclosure herein relates to delivery of fluids from, for example, a fluid delivery system (e.g., an infusion apparatus with a connected replaceable fluid dispenser, such as a syringe). More particularly, the disclosure relates to pressure priming the infusion apparatus (e.g., in low flow rate fluid delivery instances).
Infusion devices are used for the delivery of medical fluids in various situations, e.g., such as the delivery of medical fluids for an extracorporeal blood circuit, drug infusion, etc. For example, infusion devices may be usefully applied for infusing an anticoagulant in an extracorporeal circuit operatively associated with a machine for extracorporeal blood treatment. Such extracorporeal treatments may include removal of blood from the patient, external treatment thereof away from the human body, followed by its return to the patient. For example, extracorporeal blood may be made to circulate through a blood circuit comprising, in general, an arterial line, or blood removal line, which takes the blood from the patient to a blood treatment device (e.g., a dialyzer filter) and a venous line, or blood return line, which returns the treated blood to the patient.
To reduce the risk of coagulation of the extracorporeal blood, infusion of an anticoagulant, such as heparin, for example, into the extracorporeal circuit may be used (e.g., generally into the arterial line, through an infusion line connected pre-filter, with relatively low infusion flow rates). An infusion device that may be used, for example, to deliver the anticoagulant may include an actuation apparatus operating on a fluid dispenser, such as a syringe. For example, the actuation apparatus may include a pushing element, operable on command of a linear actuator, to push or displace a plunger of a syringe containing the anticoagulant at an advancement rate which is predetermined (e.g., relatively slow). For example, in a dialysis treatment, the syringe may contain a quantity of anticoagulant necessary for several hours of treatment. The pushing element and the actuator may be part of the extracorporeal treatment machine (e.g., a dialysis machine), while the syringe may be of the single-use type (e.g., a disposable or replaceable fluid dispenser).
Likewise, alternatively, to reduce the risk of coagulation of the extracorporeal blood, an anticoagulant, such as a citrate, for example, provided into the extracorporeal circuit may be used (e.g., generally provided, pre-filter, into the arterial line as a function of blood flow rate). In the case of regional citrate anticoagulation, an infusion device (e.g., including a replaceable fluid dispenser) may be used, for example, to deliver a fluid including calcium into the extracorporeal circuit (e.g., generally into the return line, through an infusion line connected post-filter, with relatively low infusion flow rates, or directly into the patient via a venous line with relatively low infusion flow rates).
Various configurations of such extracorporeal treatment machines or systems, as well as other apparatus that employ infusion devices, may include components and/or operational parameters that present a pressure and/or stiffness which operate against the delivery of fluid from the infusion apparatus. One or more of the pressures operating against fluid flow from an infusion apparatus may be monitored in the system (e.g., pressures measured at a pre-filter position in the system, measured at the return line, etc.). When a fluid dispenser (e.g., syringe) of an infusion apparatus is replaced during operation by a replacement fluid dispenser (e.g., a replacement syringe), such pressures and/or stiffness which operate against the delivery of fluid may prevent delivery of fluid into the system from the replacement fluid dispenser for an undesirable length of time (e.g., due to use of a relatively low infusion flow rate).